WHAT is the collective name for a group of crime writers? An alibi, maybe? A threat? Does anyone know if crows definitely have copyright on “a murder”?

Whatever it is – would “a suspicion” work? – it is surely applicable this afternoon. September in the BrewDog pub in Stirling and a gathering of crime writers are currently raising a glass to this year’s Bloody Scotland festival.

A table or two away, Abir Mukherjee is looking over his shoulder to say hello. If he wasn’t talking to me, he would be over there too. Instead, he’s here discussing racism, the Raj and the idea of belonging.

Belonging is the appropriate word this afternoon. Mukherjee’s new crime novel, Death in the East, is his fourth after all. So, really, he should feel right at home. Four published books make him a writer now, right? Yes and no, he suggests, as he sips his IPA. He still has a sense of imposter syndrome. “Oh God, it’s continuous. I still have it every morning. I feel more confident saying ‘I’m a writer,’ but even yesterday when we were hiring a car, I had to look at my PR person and ask, ‘can I say ‘writer?’”

I think it’s safe to say he can. Death in the East is the latest historical adventure featuring fictional detectives Captain Sam Wyndham (former Scotland Yard detective war veteran and opium fan) and his Bengali colleague Sergeant Surrender-Not Banerjee. Set in India in the 1920s, Mukherjee’s books have already attracted interest in Hollywood and famous fans such as Ian Rankin and Val McDermid.

Death In the East explains why. It is both a satisfying locked-room mystery and a sly take on current affairs. Half of the book is set in India, the other in London in 1905 when Jewish immigrants in the East End were being persecuted. Jump forward a century and you might argue has very much changed?

Mukherjee thinks not. “I spent the last 15 years living in the east end of London and what struck me was that 100 years ago the same streets that are now packed with Bangladeshi Muslims were packed with East European Jews who were fleeing from persecution. And they were in the same jobs and the press were reacting in exactly the same way that they react to Bangladeshi Muslims today.”

Inevitably issues of identity, nationalism, historical memory (historical amnesia, too) and cultural hybridity course through Mukherjee’s hugely entertaining novels. Like their creator, they are both good-humoured and socially engaged. On his Twitter feed Mukherjee describes himself as “Scottish, Bengali, generally confused.” And that same complexity is there in his work and in his conversation.

There’s also an underlying sense of hope in both, too. The world is depressing and scary, Mukherjee says. “But I’m an optimist. This is a very unfashionable thing to say. But I am an optimist in the people that we are.

“There’s a lot of fear around immigration. And a lot of divisiveness. People say that integration doesn’t work. But I’m living proof that it does.”

Well, indeed. Born in London, raised in Hamilton, Mukherjee, 45, is a walking endorsement of British multiculturalism. His Bengali Hindu father came to the UK in the 1960s with three quid in his pocket. His mum was a Bengali immigrant too. But he frames their story as a positive one.

“My parents experienced racism. I experienced racism growing up. But this country gave my family opportunities. It gave my mum and my dad opportunities that they didn’t have in their own country.”

Their story, he suggests, owes as much to class as race. “We have two problems in this country. One is gender and the other is class. Race exacerbates everything. If you’re working class and you’re black or brown your situation is much worse. For me, I have more opportunities than a white working-class boy who grew up at the same time as I did five miles away in Govan.”

You can see that in his contemporaries, he suggests. “Our whole community are doctors, engineers, lawyers. You go to the Outer Hebrides you’ll still find Bengali doctors.”

Bengali-Brits are “pretty much at the top of every field,” he suggests. He cites Baroness Chakrabarti and head of counterterrorism, Neil Basu. “We hear about the 1.3million Muslims there are in this country. We never hear about the 1.1m people of Hindu or Sikh descent. And it’s not because it’s a religious issue. It’s just that people who came from India from Hindu or Sikh backgrounds came for the most part as professionals or entrepreneurs. And that’s a very different from the Muslim experience of those who came across as working class.”

But what’s really positive, he adds, is that the education attainment levels of Bangladeshi Muslims are outperforming the mean. “You see people integrating. People come to this country because this country is special. If you go to France, you don’t see the same opportunities. You don’t see it in America.”

Well maybe, but it often hasn’t felt like that over the last year or two. The Windrush scandal, the Home Office’s hostile environment policy and a rise in racist attacks suggests Britain isn’t as tolerant as it could be.

“We always have the choice to give into fear or stand up to it. We always have a choice, as the working class did in Cable Street, as everyone did against Enoch Powell and the National Front.”

It’s as much about economics as anything, he argues. “Our economic system collapsed in 2007 and we haven’t replaced it. And the fact is the richest two or three per cent are getting richer and everybody else feels like we’re getting poorer. And it’s much easier to blame immigrants for that than saying, ‘Well, nobody pays enough tax.’

“The fact is immigrants statistically add over £2000 to GDP per head. These are our carers; these are our doctors. They’re not just our cleaners.”

Mukherjee’s novels are also reminders of our sometimes problematic imperial past. At one point he hopes to write a book about the Bengal famine of 1943 and Winston Churchill’s complicity in it. But he’s not sure he is ready yet.

“I still don’t feel emotionally ready to do that because it is a very tough subject and I want to do it at the right time; when I feel I’m a good enough author to do it.”

That may reflect the fact that he is still relatively new at this. He started writing the first Wyndham-Banerjee novel in 2013, A Rising Man, which is set against a backdrop of the Amritsar massacre, and it came out in 2016. Before that Mukherjee had spent decades working as an accountant, like his father.

When he left university, he joined the accountancy firm Touche Ross in Glasgow. In his first job he worked under none other than Fred Goodwin, aka “Fred the Shred.” After five years he moved to London where he worked in mergers and acquisitions. “I spent the next 15 years effectively working in something I really wasn’t suited to.”

He also had a ringside seat as the masters of the universe crashed the global economy. “I saw all the excesses,” he admits.

In 2010 he joined a financial house in based out of Mauritius which was majority-owned by one shareholder. He and his wife Sonal lived in a company house on the beach. Which sounds fun until you realise the company was like something out of the TV show Succession.

“One guy with three daughters and three sons in law and it was all power politics. That was a bit of an eye-opener for me in terms of how personalities and ego can trump common sense any day of the week.

“And if you want to look at the issues around our financial system far too often that’s the case. It’s a game to too many people. Very few people know what’s going on. It’s a money-go-round.”

And the problems have not gone away, he adds. “There are problems in European banking, especially German banking. We are already seeing the beginning of that with Deutsche Bank. But there’s more that’s coming.”

He still keeps his hand in. He is a partner in a firm with three of his uni friends. “When I told them, I was going part-time they said, ‘we thought you went part-time years ago.”

But he is cutting back though. “I’m technically doing one day a week.” And if a TV adaptation of the books is confirmed he will go full-time as a writer.

He has sold the rights to the American producers behind House of Cards. Kunal Nayyar, best known for his role in the Big Bang Theory has expressed an interest in playing Surrender-Not and has come on board as an executive producer and a pilot script has already been written.

In the meantime, Mukherjee is hard at work on book five of the series. Then he might take a break from Wyndham and Banerjee for a while. He wants to write a book about the immigrant experience of his parent’s generation “because it’s a very positive message and we forget that these days.”

He also wants to write a book about radicalisation. “Somebody needs to explore what it is that radicalises people. We talk about Islamic radicalisation. What about right-wing radicalisation? It stems from the same thing. Lack of opportunity. If we talk about integration, integration to me is about access to the opportunities this country gives people. The fact is I’ve been given opportunities that these working-class Muslims don’t have or these white working-class boys on sink estates don’t have. By those tokens, I’m more integrated than either.”

Abir Mukherjee knows he belongs. He wishes others could say the same.

Death in the East, by Abir Mukherjee is published by Harvill Secker on Thursday, priced £14.99. The author is appearing at Waterstones Edinburgh West End on Wednesday, November 20 at 6.30pm as part of Book Week Scotland. Tickets cost £2.